Body-centered-cubic martensite and the role on room-temperature tensile properties in Si-added SiVCrMnFeCo high-entropy alloys

Yong Hee Jo, Junha Yang, Won Mi Choi, Kyung Yeon Doh, Donghwa Lee, Hyoung Seop Kim, Byeong Joo Lee, Seok Su Sohn, Sunghak Lee

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

We present a new class of metastable high-entropy alloys (HEAs), triggering deformation-induced martensitic transformation (DIMT) from face-centered-cubic (FCC) to body-centered-cubic (BCC), i.e., BCC-DIMT. Through the ab-initio calculation based on 1st order axial interaction model and combined with the Gibbs free energy calculation, the addition of Si is considered as a critical element which enables to reduce the intrinsic stacking fault energy (ISFE) in SixV(9-x)Cr10Mn5Fe46Co30 (x = 2, 4, and 7 at.%) alloy system. The ISFE decreases from -30.4 to -35.5 mJ/m2 as the Si content increases from 2 to 7 at.%, which well corresponds to the reduced phase stability of FCC against HCP. The BCC-DIMT occurs in all the alloys via intermediate HCP martensite, and the HCP martensite provides nucleation sites of BCC martensite. Therefore, the transformation rate enhances as the Si content increases in an earlier deformation range. However, the BCC-DIMT is also affected by the phase stability of FCC against BCC, and the stability is the highest at the Si content of 7 at.%. Thus, the 7Si alloy presents the moderate transformation rate in the later deformation range. Due to the well-controlled transformation rate and consequent strain-hardening rate, the 7Si alloy possesses the superior combination of strength and ductility beyond 1 GPa of tensile strength at room temperature. Our results suggest that the Si addition can be a favorable candidate in various metastable HEAs for the further property improvement.

Original languageEnglish
Pages (from-to)222-230
Number of pages9
JournalJournal of Materials Science and Technology
Volume76
DOIs
Publication statusPublished - 2021 Jun 20

Keywords

  • Deformation-induced martensitic transformation (DIMT)
  • High-entropy alloy (HEA)
  • Phase stability
  • Stacking fault energy (SFE)

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Polymers and Plastics
  • Metals and Alloys
  • Materials Chemistry

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